FTB 09-30-2018: Final FTB of the 2018 Season

Issue Date: 9/30/2018
Issue Time: 7:10 AM


NOTE: This is the final scheduled Flood Threat Bulletin of the 2018 season. However, additional Bulletins may be necessary next week to cover the potential heavy rainfall threat over western Colorado. If a flood threat appears, we will be doing special Flood Threat Bulletin(s) as warranted.

A weak cool front pushed southward overnight across eastern Colorado, bringing cooler temperatures and a slight increase in low-level moisture. Ultimately, this has resulted in low clouds, fog, and a couple pockets of light drizzle across the eastern plains this morning. The clouds will attempt to hang on as long as possible today, clearing from west to east as the day wears on. This means highs in the upper 60s and 70s for the Urban Corridor, low-to-mid-80s across western portions of the Southeast Plains, with temperatures struggling to get out of the 50s near the eastern border north of Highway 50, and mid-60s south of Highway 50.

For the High Country, the shallow cool air and moisture from the east won’t have an impact, and instead another day of mostly sunny skies and warm temperatures are in store. As the day wears on, scattered high- and mid-level clouds will stream across the area, thanks to a pocket of moisture associated with an upper-level shortwave from the Great Basin and outflow from Hurricane Rosa. A couple isolated, high-based showers, and perhaps a weak thunderstorm or two, will develop over the higher terrain in association with these moisture streams, producing mainly light rainfall and gusty winds. Moisture is too shallow for anything more. For more details on timing and rain rates, please see the zone-specific discussions below.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below (hover over threat areas for more details). For Zone-Specific forecasts, jump below the map.

Flood Threat Legend

Zone-Specific Forecasts

Urban Corridor, Palmer Ridge, Northeast Plains, Southeast Plains, and Raton Ridge:

Cool and cloudy for most to start the day, with the low-level clouds and fog mixing out from west to east. A wide range of temperatures are expected, with eastern portions of the Northeast Plains and Southeast Plains (north of Highway 50) struggling to get out of the 50s, the Urban Corridor expected to be in the 60s and 70s, and western portions of the Southeast Plains reaching into the mid-to-upper 80s. Pockets of light drizzle are expected during the morning and early afternoon hours, mainly over the Northeast Plains, but very little accumulation will result.

Front Range, Northern Mountains, Northwest Slope, Central Mountains, Southeast Mountains, Grand Valley, San Juan Mountains, Southwest Slope, and San Luis Valley:

Mostly sunny and warm will be the main weather story today, with a slight uptick in moisture and downtick in winds lessening (somewhat) the fire danger as compared to yesterday. Pockets of mid- and high-level moisture will stream over the High Country, resulting in an increase in clouds as the day wears on, with a couple isolated, high-based showers (and a weak thunderstorm or two) expected from the late afternoon and into tomorrow. Moisture is shallow and high-based, so not much rainfall is expected; the main impacts will be gusty winds and light rainfall. Maximum rain rates will remain below 0.15 inches/hour.

Timing: 5 PM – 11 AM